A semiconductor device including a compound semiconductor represented by GaN, AlN, InN, or mixed crystal thereof is popular as a high-power electronic device or a short-wavelength emission device since the semiconductor device has excellent material characteristics.
As a high-power electronic device, research and development of a field-effect transistor (FET) (particularly, a high electron mobility transistor (HEMT)) is in progress. Therefore, an application of such a high-power high-efficiency amplifier or a large-power switching device is expected to be implemented.
An example of the related art is disclosed in Japanese Unexamined Patent Application Publication No. 2002-359256.